The latest installment in the Diablo game series has become the fastest selling PC game in history

Blizzard Entertainment today proudly announced that the Diablo III video game racked up 3.5 million units sold in the first 24 hours, and added to that tally through the first week.

After the first week, more than 6.3 million gamers are now playing Diablo III, still excluding Korean gamers playing Diablo III at Internet cafes. That number also doesn't include 1.2M gamers that received Diablo III for free when they signed up for a one-year subscription to World of Warcraft.

Meanwhile, Diablo III sales are expected to creep up in the weeks to come, as casual RPG gamers enter the mix.

"We're definitely thrilled that so many people around the world were excited to pick up their copy of Diablo III and jump in the moment it went live," said Mike Morhaime, Blizzard CEO and co-founder, in a press statement. "We also regret that our preparations were not enough to ensure everyone had a seamless experience when they did so. I want to reaffirm our commitment to make sure the millions of Diablo III players out there have a great experience with the game moving forward, and I also want to thank them for their ongoing support."

More than 8,000 retailers worldwide offered the game in North America, Europe, South Korea, Australia, and other parts of the world -- and digital downloads were available in the same markets, plus a handful of other locations.

The Diablo game trilogy, plus expansions and later modifications, have proven to be some of the most popular RPG video games ever. Diablo II launched in the summer of 2000, and generated 4M units sold in the first year.

Everything seems to be looking up for Blizzard, even though there are early reports of game account theft and related problems. Since Diablo III has a feature such as the real money auction house, so players can earn real money, and now there is a question of account theft and fraud. Forbes recently published an article related to Diablo III hacking, and whether people have traditionally been prosecuted for digital game theft.

Blizzard can look forward to other problems popping up here and there, but with the support of millions of gamers, should be able to handle any bumps in the road.

Well you had to sign up for a year of WoW to get D3 for "free" and so they really didn't give anything away. It's likely they did the math on that and realized the number of people who would both pay for another year of a dying MMO AND D3 was pretty small, and my guess is they made quite a bit of extra money on that deal. Yes, some people would do both, but 1.2 million? Not even close.